As piezoelectric materials, lead-based ceramics, such as lead zirconate titanate (hereinafter referred to as “PZT”), having a perovskite structure are common.
However, PZT contains lead at an A site of the perovskite structure. Therefore, the influence of a lead component on environment has been considered as a problem. In order to overcome this problem, a piezoelectric material using a perovskite type oxide which contains no lead has been proposed.
As a typical non-lead perovskite type piezoelectric material, for example, barium titanate represented by general formula BaTiO3 (hereinafter referred to as “BTO”) may be mentioned.
For example, PTL 1 has disclosed a BTO ceramic having a high piezoelectric constant in which by performing two-stage sintering at different temperatures, the average grain diameter is controlled in a range of 1 to 2 μm and the maximum grain diameter is controlled to 5 μm. However, a strain amount of a piezoelectric element formed using a BTO ceramic was not yet sufficient.